Displace Modifier on an object
First you want to unwrap your pot, which you said you already have.
Next you want to make sure that you either have sufficient subdivisions or add a subd modifier at the top of the stack so the displacement modifier has enough geo to actually displace.

Add the displace modifier, go to the Texture Properties tab and select Image or Movie as the Type and load the image you posted.



Back on the modifier tab, set the Texture Coordinates to UV, the UV Map to the map you made above and adjust the strength as you see fit.